Fastener



FIG. 1 is a front perspective view of a fastener showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a top plan view thereof, the bottom plan view being symmetrical; and,

FIG. 5 is a rear elevation view thereof.

Elements shown in broken lines form no part of the claimed design. 

CLAIM The ornamental design for a fastener, as shown and described. 